COE compatability?

[SuzFromOz]

Hi Folks,
I have a question...does the numerical value of the glass COE have any relevance to compatability (if they are not identical). For example...I am playing with some czech shampoo glass at the moment. I remembered I had some scraps of czech glass a friend gave to me, and I assumed they were compatible..I did a couple of beads with a tiny bit of pearl glass on top... Now, the czech is 104 (?) and the shampoo I just found out is about 94. So, my question is, would it be safer to put a bit of pearl decoration on a bulleye bead for eg, rather than the normal czech, as they are numerically closer in COE value?

This is a theoretical question - I dont intend to mix glasses, but it just made me think about it.....

Suzanne

[Jude Rose]

Hi Suz-

here's a great link that answers your question perfectly:
https://www.cdvkiln.com/ris-bullseye.htm

"The viscosity characteristics of a glass are equally as important as its expansion characteristics. Together, these two properties determine whether one glass will fit another." This is probably an great explanation of why sometimes white-a very 'drippy' glass, oftens cracks when used as a base then encased with a 'stiffer' transparent. I also I read on Jan & John's site that their shampoo glass isn't co-efficient with even other Czechs. So it's going to take some experimentation to succeed.
Here's a link to the Check site with tips on how to mix your glass if you decided to try it in the future:
http://www.checkglass.com/faq's.htm